1. Field of the Invention
This invention relates to providing supplemental thermal energy to vehicles having living areas, and more particularly to providing supplemental heat to over-the-road and marine craft having rooms and domestic water to be heated.
2. Discussion of Prior Art
Vehicles of many types have been used to provide temporary living or working quarters. These include self-propelled over-the-road vehicles, such as so-called recreational vehicles powered by internal combustion engines. Also, self-propelled vans have been used as mobile work spaces, such as for providing medical services at remote or movable locations in a city. Other self-propelled vehicles include boats in which internal combustion engines provide the primary power source. Other non-self-propelled vehicles, such as trailers, have been used to provide shelter for temporary living, such as for vacation or recreation. Also, trailers are used to provide space for performing work, such as at construction sites or performing atmospheric sensing at remote locations.
All of these vehicles are characterized by the need to provide heated space, in the form of at least one room. In general, many separate rooms or work areas are provided. Also, sanitary facilities are provided in such vehicles, and include plumbing fixtures such as sinks, showers, and toilets that use domestic water, especially heated water.
The term "vehicle" is used herein to refer to all of these types of vehicles, whether or not self-propelled and whether an over-the-road or water vehicle, so long as there is a space to be heated in the vehicle and/or a requirement that heated domestic water be available for use. The term "vehicle" may also include the above type of vehicle that is also provided with a main power source, such as an internal combustion engine, that has a primary function of propelling the vehicle on land or water. Customarily, those main power sources are heated when not in operation, so that they will start readily when the vehicle is to be moved.
The main power source of such vehicle is turned off when the vehicle arrives at the destination, and reliance is placed on a supplemental source of thermal energy. Such supplemental thermal energy sources include diesel-fired and gasoline-fired burners, such as those disclosed in U.S. Pat. Nos. 2,726,042 and 3,877,639. These supplemental burners transfer heat to a small mass or volume of liquid in a thin jacket that surrounds the burner's combustion chamber. The thin jacket substantially limits the mass and volume of liquid that is in heat transfer relationship with the combustion chamber.
In applicant's experience with such burners, the liquid volume in the thin jackets is only about 0.26 gallons, and a typical system, including conduits and liquid-to-air heat exchangers, may only have a two and one-half gallon liquid volume, including the 0.26 gallons in the thin jackets. Further, such mass and volume of the liquid in the thin jackets are not selected according to the operating characteristics of the auxiliary burners.
Other systems used with such vehicles include relatively small domestic hot water tanks, such as those holding eleven gallons. The domestic water is heated by a heat exchanger that uses energy from the main engine. Alternatively, the domestic water is heated when the supplemental burner is operated for heating room air. The operation of the burner is not generally controlled in response to the demand for hot domestic water. For example, U.S. Pat. No. 236,849 issued in 1881 discloses pipes that supply heat to both a domestic water tank and radiators for room air heating.